Metal spinning, often called spin forming, is a cold metalworking process in which a flat metal disc affixed to a lathe mandrel is rotated at high speeds and formed by shaping tools. A metal spinner applies pressure to the rotating disc, which is called a blank, using several tools, which are called spoons, to shape the metal over a mandrel. This pressure can be applied by a single tool or by multiple tools. The finished product should have no wrinkling or warble, and the process is quick and cost-effective. An average metal piece will take only five to ten minutes to be formed, and very little metal waste is produced per part.
The metal spinning process can form various kinds of metals, including aluminum, titanium, stainless steel, copper and many other metals. Sheet metal spinning generates products used in the aerospace, food processing, healthcare, defense contracting, pharmaceutical, paper and many other industries. Engine parts, nozzles, tank heads, funnels, freezers, mixing bowls, filter housings, pressure vessels and cartridges are just a few examples of the many parts that are produced by metal spinning. Metal spinning can be done by hand, but a CNC metal spinning machine, which is short for computer numeric controlled machine, usually produces metal spun products. Flow forming is a popular alternative to spin forming; it is an advanced process that allows variation in wall thickness of the product. Tube spinning, which produces cylinder shapes, and shear spinning, which produces cone or contoured shapes, are the two forms of flow forming. Alternative cold working processes like hydroforming are available when metal spinning and other methods are not appropriate.Metal spinning is a cost-effective choice for forming metal, though it is usually used for smaller runs compared to other metalworking processes. When spinning cannot meet more complex design specifications, flow forming is often used. It is the main alternative to standard metal spinning and produces hollow, symmetrical shapes by using rollers to extrude a cross-sectional area of a pre-formed metal part, which is often called a blank or perform. The thickness of the part is determined by the gap that is maintained between the mandrel and the rollers. This gap may change in order to produce a product with inconsistent or uniform wall thickness. The end product parts are round in cross section but may be straight sided cones or contoured shapes. The metal that is worked into a shape is either preformed by welding or in sheet form. Heat resistant steels such as stainless steel are good materials for the flow forming process because their ductility and tensile strength are ideal for cold extrusion. Flow forming can create seamless, single pieces that have a wide range of design flexibility with increased tensile strength.
Tube forming, a flow forming method, takes tubular performs and cold works them via rollers and a mandrel to produce tubing. When shapes are made with one closed end (like a vessel), the bottom of the preform rests against the face of the mandrel while the material is moved in the same direction as the rollers. This is called forward flow forming. Reverse flow forming is a technique that produces a part with two open ends (like a tube). The force applied by rollers pushes against a serrated ring at the end of the mandrel, which compresses and extrudes the material. Shear spinning, the second method of flow forming, produces cone-shaped metal products by a flat blank that is sheared by rollers over a rotating mandrel. The diameter of the blank does not change, but the thickness decreases depending on the angle of the mandrel. No material is lost in this process. Hydroforming is an alternative to standard metal spinning and flow forming. In this process, the metal flows around a punch instead of being stretched with dyes by using a high pressure hydraulic system to create parts with very consistent thickness. There are four types of hydroforming. The most common type, tube hydroforming, is generally performed at low pressure and produces tubular parts with high integrity and structural performance. Panel hydroforming is a high pressure process that manufactures products for the automotive and aerospace industry. The third type, low pressure hydroforming, involves reshaping tubes when the cross-section definition is not strict. High pressure hydroforming, the fourth method, reshapes tubing more than the other three methods. In this type of hydroforming, the length-to-circumference ratio can change up to 50 percent.When using metal spinning to fabricate a product, it is important to note the supplier's output capability. Some metal spinning manufacturers are not capable of short run orders and may have limitations as to the diameter and thickness of the final product desired. However, many suppliers offer sizes from a fraction of an inch to over six feet in diameter. Sometimes, a metal spinning manufacturer will only have the capacity to spin a certain type of metal, such as stainless steel or aluminum. Though not all manufacturers can offer every type of spinning service, metal spinning can mean lower tooling costs because spinner dies are simpler and cheaper. Spinning tooling can also be made in-house by many spinning shops, meaning shorter lead times. The spinning process often work-hardens the metal product as it is being shaped, providing a stronger end product. The metal spinning business continues to grow as the process becomes better through technological advances.
Images Provided by Acme Metal Spinning, Inc.
- An uncontrolled deformation pattern perpendicular to the surface of a sheet caused by compressive stresses.
- Computer Numeric Controlled.
- The sheering tendency of sheet metal material that occurs via the bending of the same plane.
- The reforming of metal, usually, but not necessarily, conducted at room temperature. Also referred to as cold forming or cold forging. Contrast with hot working.
- Having the same center, as concentric circles; having the same axis, as concentric cylinders.
- The drawing of deeply recessed parts from sheet material through plastic flow of the material when the depth of the recess equals or exceeds the minimum part width.
- A tool, usually containing a cavity, that imparts shape to solid, molten, or powdered metal primarily because of the shape of the tool itself.
- A circular plate with a hole in the center contoured to fit a forming punch; used to support the blank during the forming cycle.
- The amount of permanent extension of the material before it fractures.
- The bending of a piece 180°, usually done in two steps after a piece has been created via spinning. First a sharp angle is created then closed via a flat punch and die.
- A device used to secure a workpiece.
- Machine tool for shaping metal or wood; the workpiece turns about a horizontal axis against a fixed tool.
- A tapered steel form used to support metal as it is being formed. Also called a Chuck.
- The reduction of the cross-sectional area of metal in a localized area by uni-axial tension or by stretching.
- Texture of steel that appears like an orange, either from the steel mill or after forming.
- Bending metal a greater amount than called for in the finished piece to allow for springback.
- The realigning or adjusting of dies or tools during a production run; not to be confused with the operation setup that occurs before a production run.
- This is a general term used to describe most press workings.
- Used most often as a spacer within the spinning machine.
- The form to which the sheet metal is formed to simulate.